A robot surgeon has been taught to perform a delicate procedure—stitching soft tissue together with a needle and thread—more precisely and reliably than even the best human doctor.

The Smart Tissue Autonomous Robot (STAR), developed by researchers at Children’s National Health System in Washington, D.C., uses an advanced 3-D imaging system and very precise force sensing to apply stitches with submillimeter precision. The system was designed to copy state-of-the art surgical practice, but in tests involving living pigs, it proved capable of outperforming its teachers.

Currently, most surgical robots are controlled remotely, and no automated surgical system has been used to manipulate soft tissue. So the work, described today in the journal Science Translational Medicine, shows the potential for automated surgical tools to improve patient outcomes. More than 45 million soft-tissue surgeries are performed in the U.S. each year. Examples include hernia operations and repairs of torn muscles.

“Imagine that you need a surgery, or your loved one needs a surgery,” says Peter Kim, a pediatric surgeon at Children’s National, who led the work. “Wouldn’t it be critical to have the best surgeon and the best surgical techniques available?”

Kim does not see the technology replacing human surgeons. He explains that a surgeon still oversees the robot’s work and will take over in an emergency, such as unexpected bleeding.

“Even though we take pride in our craft of doing surgical procedures, to have a machine or tool that works with us in ensuring better outcome safety and reducing complications—[there] would be a tremendous benefit,” Kim says. The new system is an impressive example of a robot performing delicate manipulation. If robots can master human-level dexterity, they could conceivably take on many more tasks and jobs.

STAR consists of an industrial robot equipped with several custom-made components. The researchers developed a force-sensitive device for suturing and, most important, a near-infrared camera capable of imaging soft tissue in detail when fluorescent markers are injected.

“It’s an important result,” says Ken Goldberg, a professor at UC Berkeley who is also developing robotic surgical systems. “The innovation in 3-D sensing is particularly interesting.”

Goldberg’s team is developed surgical robots that could be more flexible than STAR because instead of being manually programmed, they can learn automatically by observing expert surgeons. “Copying the skill of experts is really the next step here,” he says.